Sensors arranged on a computer system and able to detect the presence of a person are generally known. Such systems have the advantage that a person who is working on a computer system is not necessarily obliged to make inputs into the computer system to prevent adoption of a limited energy-saving operating mode, for example, the activation of a screensaver or an idle state. For this purpose, a zone in the vicinity of the computer system is detected, for example, a zone in front of a display device.
If the orientation of the sensor alters, so that it detects a zone in which a person is not present even though a person is working on the computer system, then the computer system is no longer able to detect the person. If a user ceases to enter data, it may happen that the computer system is put into an idle state or a sleep state, even though a user is using the computer system passively, for example, by reading an article on the display device.